Sway back sewers are a shapely lot. Getting the curves of a garment to meet our needs is a basic adjustment that I do all the time.
I’m working with Vogue 8931 and the pattern has a fold on the centre back. Easy peasy.
If you need to do a sway back adjustment, you’ll need some shaping hence, convert the centre back fold to a centre back seam.
On the lining piece above, I’ve marked where the centre back seam should be. But I’ve also allowed for a centre back fold for a bit of jacket wiggle room.
The result is the lining pieces match where they should but you have a fold so the lining moves with you. I’ve had it rip before and I’m still haunted by that sound (shudder).
This new centre back seam gives you more shaping for your sway back. I also lower the centre back hem by 1.5cm. Now that’s shaping where I need it.
By the way, I apply this same technique on knit fabrics too.
Don’t just look at what I’ve done, go to some real references.
Singer Tailoring – 1988,
Jackets for real people by Alto, Neall and Palmer – 2006,
New Simplicity Sewing Book – 1979
Easy, Easier, Easiest Tailoring by Palmer and Pletsch – 1977
velosews 
You always achieve such a nice fit.
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I know I need to do a swayback adjustment; I am just inconsistent with doing it. Thank you for reminding me!
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You've written quite a little series about making this jacket :). I always add a centre back fold to lining – I grew up with the old Vogue patterns and they always put a fold in the back – with herringbone stitch as I recall 🙂
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I am sorry but that simply is NOT a swayback adjustment. That's a back waist adjustment. A swayback adjustment is a horizontal dart taken out on the pattern paper before cutting. The dart is widest at the centre back, tapering to nothing at the side seam. It is made approximately 3″ below the waist line. It shortens the centre back but does not draw the fabric in towards the body.
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